Sulfidation Resistance

HAYNES® 188 alloy has very good resistance to gaseous sulfidation envronments encountered in various industrial applications. Tests were conducted at 1400°F (760°C) in a gas mixture consisting of 5 percent H2, 5 percent CO1, 1 percent CO2 , and 0.15 percent H2S, balance Ar. Coupons were exposed for 215 hours. This is a severe test, with equilibrium sulfur partial pressure of 10-6 to 10-7 and oxygen partial pressures less than that needed to produce protective chromium oxide scales.

Sulfidation Resistance at 1400°F (760°C)

215 hours in an atmosphere of 5% H2 + 5% CO + 0.15% H2S + Balance Ar

Alloy

1400°F (760°C)

1600°F (871°C)

Metal Loss

Average Metal Affected

Metal Loss

Average Metal Affected

mils

μm

mils

μm

mils

μm

mils

μm

25

0.5

13

1.5

38

1.1

28

5.3

135

188

1.6

41

3.3

84

1.7

44

5.7

145

556®

3.1

77

4.9

124

6.2

157

16.4

417

310

6.2

157

9.1

231

8.3

211

14.1

358

617

5.0

127

10.8

274

3.8

97

17.2

437

800H

7.1

180

11.2

284

7.9

201

>27.6

>701

625

6.6

168

12.6

320

Partially Consumed

X

-

-

>29.5

>749

-

-

>21.7

>551

Schematic Representation of Metallographic Technique
Used for Evaluating Environmental Tests